The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Internal combustion engines are known to employ valve stem seals to regulate oil to the valve guide and minimize oil from entering a combustion chamber. However, the weakness of the current art is that pressure from the combustion chamber and an exhaust port of an engine can affect the function of primary sealing lips of valve stem seals. Gas lips, which provide an additional seal, have been applied, but pressure acting on such a gas lip can cause the orientation of a primary sealing lip against a valve stem to change and result in improper function. Accordingly, it would be desirable to provide a valve stem seal that can relieve pressure while continuing to prevent excessive oil from entering the combustion chamber.